Telephone-exchange system.



E. R. LUNDIUS. TELEPHONiE EXCHANGE SYSTEM. AHLICATION FILED MAY 1|, 19H}.

1,295,909., Pateflted Ma1'.4,1919.

TELEPHONE-EXCHANGE SYSTEM.

Specification of Letters Patent.

Patented Mar. 4, 1919.

2 Application filed May 11, 1918. Serial No. 233,915.

To all whom it may concern:

citizen of the such systems of wlnch employ trunk circults for establishlng Switchboard or A extends from provided a cord that I, ERIC R. LUNnIUs, a United States, residing at in the county Be it known Brooklyn,

useful Improvements in. Telephone-EX- change Systems, of which the following is a full, clear, concise, and exact description.

his invention relates to telephone exchange systems, and more particularly to the central energy type connections from a switchboard operators position to a desk-operators posltion.

In systems of this type, the switchboard 'operators link circuit is equipped with'a key for ringing purposes, and when connection is made with a trunk circuit extending to a desk-operators position, the switchboard or originating operator may ring thereon and continue to ring even after the desk operator .has answered. In such employed, when ringing v :desk operator has answered, very disagreesystems heretofore contlnues after the able clicks are produced the answering operator.

It is the object of this invention to produce a system of this character in which the production of such disagreeable clicks in the receiver of the answering operator is avoided.

In accordance with this invention, a normally open trunk circuit extending from a switchboard operators position to another desk is provided with means which functions when the desk operator answers to connect across the trunk circuit a relay which is non-responsive to ringing current, but which responds to direct current connected with the trunk circuit upon the disconnection of ringing current therefrom to complete the connection to the desk.

For a more complete understanding of this invention, reference should be had to the following description considered in connection with the accompanying drawing illustrating one embodiment thereof.

' .As shown inthe drawing, a trunk circuit a first to a second switc board. At the first switchboard which may be designated as switchboard X, there is circuit B, by means of which in the receiver of 7 connection may be made from a calling tele-' phone line (not shown) and the trunk circuit A. This cord cir'cuit B' may also be cmof Kings, State of New York, have invented certain new and operator there- ,at may make connections with the trunk circuit in answering calls incoming thereover. The apparatus shown to the left of the dotted line l-1 is located at the switchboard X and that shown to the right of this dotted "line may be located at the switchboard Y. Theswitchboard 'X may for convenience be considered as an originating operators position, while the switchboard Y may be con sidered the desk of a chief operator, trouble operator or supervisory operator.

The operator at the originating position desiring to establish a connection to the 'desk position Y, insertsplug 5 of the cord jcircuit B into jack 6 ofthe trunk circuit A,

whereupon calling supervisory lamp 7 is 9, sleeve contacts of the 6, normal contact of relay 10,- upper normal contact of relay 12, winding of relay 8 and contact 11 of relay 12 to ground. Relay 8 in operating causes the lighting of lamp 13 over a circuit from battery through the lamp of relay l2 and the contact of relay 8 to -ound. Since the cord circuit B "is provide with a ringing key 14, the opera tor at the originatingposition, while it is not at allnecessa'ry, may actuate this ringing key,and if it is actuated, it is very desirable that connection through to the desk operator be delayed until after the ringing key has been restored to normal position. The manner in which this is brought about will more fully hereinafter appear.

, The lighting of the lamp 13 servesas a signal to the desk operator, who, upon observing the lighted condition thereof, may answer by inserting plug 20 of the cord circuit G into jack 21. There upon lamp 22 lights and relay 10 operates over a circuit from battery through the lamp 22, resistance 23, sleeve contacts of the plug 20 and the jack 21, lower winding of relay 10 and contact 24 of relay 25 to ground. Relay 10 in operating opens the circuit of relay 8, thereby causing its denergization and the effacement of the lamp 13. Relay 10 in operating also closes its contact 26, thereby including relay 12 in e is responsive to circuit of relay restoration of the ringing key tacts of relays in ircuit.

circuit with the sleeve strand of the trunk circuit, whereupon relay 12 operates. Re-

lay 12 in operating completes a lockingcir- .30 which is of high impedance to high frequency talking currents but not necessarily to low frequency ringing current. Relay 8 direct current, but is nonresponsive to ringing current. That is, while the armature of this relay 8 will be partially attracted when the wind; ing thereof is traversed by ringing current, the contact will not be maintained closed under such circumstances. Therefore it the ringing key 14 is actuated at the time relay 8: is connected across the talking circuit, the contact of relay 8 will not be closed. This contact of relay 8 controls the 25 which in turn controls the completion of the talking circuit through to the desk operator. Upon the 14. to normal position, ringing current 18 disconnected from the trunk circuit and direct current substituted therefor, whereupon relays 8 and 30 operate over a circuit from battery through the winding of supervisory relay 31, ring contacts of the plug 5 and the jack 6, contact 28 of relay 12, winding of relay 8, contact 29 of relay 12, winding of relay 30,. contact 32 of relay 10 and tip contacts of the jack 6 and the plug 5 to ground. Supervisory relay 31 also operates over this circuit to establish a shunt circuit including resistance 33 about the lamp 7, which is thereby eflfaced, indicating to the originating operator that the desk operator has answered. Upon the operation of relays 8 and 30, relay 25 operates over acircuit from battery through 'ts winding and the con- 30 and 8 to ground. Relay 25 in operating opens its normal and closes its alternate contacts. The closure of the alternate contacts connects the talking circuit through to the desk. The opening of contact 24 of relay 25 removes the short circuit from the upper wi ding of relay 10 which is thereupon included in circuit with the lamp 22. Lamp 22 is therebyetlaced. Since, while the relay 25- is deenergized the lamp 22 of: the connected cord circuit is lighted and When the relay is energized the lamp is eiiaced, this relayinay be, termed a signal control relay. Before inserting plug 20 of the cord circuit G into the jack 21 of the trunk circuit A, or immediately thereafter, the desk operator may actuate listening key 34; to connect the telephone set Ei her upon the restoration of ringing key 14 to normal position or upon the-eftacement of the lamp 7,the originating operator may actuate listening key 42 to conversation, the plugs may ntacts of relay desk.

- such iniiormation may connect this operators telephone set in circuit. Both telephone sets being connected and the talking circuit being completed by the operation of relay 25-, the operators may now converse. At the conclusion of the be withdrawn from the jacks, whereupon all apparatus is restored to normal condition.

It may happen that the desk operator connects the cordcircuit O with the trunk circuit A. without actuating. the listening key 34. When the originating operators telephone set is connected in circuit, upon the actuat'on of the listening key 35, following the efiacement of the supervisory lamp 7 this operator will find that the desk operator has not connected her telephone set in circuit. It will be necessary there fore for the originating operator to rering (or resignal) the desk operator. This is brought about by repeatedly withdrawing the plug 5 from. and reinserting it into the jack 6, thereby to cause the flashing or intermittent operation of the lamp 22 associated with the cord. circuit C. The withdrawal of the plug 5 from the jack 6 releases relays 12, 8, 30 and 25. The closure of contact 24: of relay 25 short-circuits the upper winding of relay 10, whereupon lamp 22 is lighted. The opening of the alternate 25 opens the talking conductors of the trunk circuit, and the closure of the upper and lower normal. contacts of this relay 25 connects resistances 35 and 36 in shunt of condensers 37 and 38, thereby to discharge these condensers, so that upon the subsequent energization of relay 25, the connection of the condensers 37 and 38 in the talking conductors will take place when the condensers are in discharged condition. In this manner there will be no discharge over the talking conductors upon their closure at the alternate contacts of relay 25. The reinsertion of the plug 5 into the jack 6 causes the energization of relay 12., followed in turn by the energization of relays 8, 30 and 25. Relay the lamp 22, thereby'to eflace the lamp.

The closure of th alternate contacts f relay completes the talking circuit to the The "lamp 22 will be lighted each time the plug Bis withdrawn from the jack 6. The desk operator observing the intermittent lighting of the lamp 22, actnates listening key 34 to connect the telephone set in circuit.

If a calling subscribers line is connected by way of the 5 rd circuit B and the trunk circuit A to the desk,the desk operator may then converse with the calling subscriber. If this is an information desk, the desk operator, after giving the calling subscriber be desired, may

operator who 42 to connect hating operator is reri-nging,or when the contactsin the talkin pletes the shunt circuits about'the condens- -ers '37 and 38to cause the discharge thereof. 15'

1O lmmediately operates, connecting relays 8 and 30 inbridge of the talking conductors, whereupon these two relays and the supersupervisory relay 31 causes the lamp 7 and the operation of relays 8 and 130 causes the operation of==relay 25 to close lighted upon each closure wish to signal the originating operator. This may be done by repeatedly actuating a key 40 to cause the flashing or intermittent Relays 31, 8,

upon being decnergized, opens the shunt circuit about thelamp 7 which thereupon lights. Relay 25, upon being deenergized, opensthe conductors and com- Upon the opening of contact ofkey 40, relay visory relay 31 operate. il-he operation of the efiacement of the talking c0nductors;-'i-riT he lamp 7 is ofthe contact of the key 40. The intermittentlightingof this lamp 7 serves as a signal to theoriginating may then actuate listening key the telephone set in circuit. One of the other of the operators telephone sets may be in circuit when the'origidesk operator is signaling the originating operator, so thatthe' provision of the shunt -circuits about the condensers 37" and 38 serves a very clicks wl1ich '1nay'be useful purpose reducing the produced in the operators receivers while thereril'iging' and signaling operations are taking place. What is claimed is:

,1. A telephone exchange system comprising a trunk circuit having normally open talking conductors extending from a first to a second swltchboard, almk circu t at the first switchboard, a signaling device atthe second switchboard, a -rela-y n the trunk circuit responsive to the connectlon of the link circuit therewith for operating the signaling device, a link circuit-"at the second switchboard, means in the trunk circuit responsive to the connection of the second link circuit therewith for connecting the relay in bridge of the talking conductors, V and means responsive after the e'st'ablishment of the bridge to close the normally open talking conductors.

2. A telephone exchange system comprising a trunk circuit having normally open talking conductors extending from a first to a second switchboard, a link circuit at the first switchboard, a signaling device at the second switchboard, a relay in the trunk circuit responsive to theconnection of: the link 7 circuit therewith for operating the signaling device, alink circuit at the secondfswitchboard, a pair of relays in the trunk circuit circuit therewith for bridge of the talking energizing the bridged relay over the connected trunk and first link circuits, and

for energizing the bridged relay,

responsive to the connection of thesccond link circuit therewith and cooperating to bridged relay to close'the nora second switchboard, means associated with the trunk o1'1'cu1t for slgnahng from the first to the second switchboard, a link circuit at the second switchboard, a relay,means in the trunk circuit responsive to the connection of thelink circuit *neeting therelay in bridge or the talking herewith for conconductors, and means responsive after the establishment of the bridge to close the nor- -ma1ly open talking conductors.

4. A telephone exchange -ing a trunk circuit having normally open qtalking conductors extending frorna first to "a second switchboard, a link circuit at the firstswitchboard connected with the trunk system compriscircuit, a relay, alink circuit at the second switchboard, means in the trunk circuit responsive to the connection of the second link connecting the relay 1n conductors, means for means responsive to the energization of the bridged relay for closing the normally open talking conductors.

5. A telephone exchange system comprising a trunk circuit having normally open talking conductors extending from a first to a second switchboard, a link circuit at the "first switchboard connected with the trunk circuit, a link circuit at the second switchboard, a relay, a second relay 111 the trunk :clrcuit responsive to the connection of a link circuit therewith for connecting the first -relay1n bridge of the talking conductors,

means associated with the first link circuit and a relay responsive to the energization of the bridged relay for closing the normally open talking conductors.

6. A telephone exchange system comprising a trunk circuit having talking conductors extending from a first to a second switchboard, a link circuit at the first switchboard, a signal control relay in the trunk circuit operating'over a circuit independent of the talking conductors upon the connection of the link circuit with the trunk circuit, a link circuit at the second switchboard, means in the trunk circuit responsive to the connec tion of the second link circuit therewith for connecting the signal control relay in bridge of the talking conductors, and a second sig nal control relay operating after the estabto s x ending from a lishn ent of the bridge to close the normally open talking conductors,

relays in the trunk circuit; responslve to the connection of the second link circuit therewith and cooperating to connect the signaling control relay in bridge of the talking conductors, means associated with the f st link circuit for energi i g t e bridge relay, and a second signal control relay responsive to the energization of the bridged relay. a

8. A telephone exchange system compris- 11; a trunk circuit havi g normally ope tallring'oond cto s extending from a. fir to a second switchboard, a link circuit at the first switchboard connected'with the trunk circuit, means in the link circuit. for connecting a source of ringing current with the talking conductors, a source of direct current at the first switchboard, a link circuit at the second, switchboard, a'relny connected in bridge of the talking conductors upon the connection of the second link circuit with the trunk circuit and non-responsive while ringing current is connected therewith but responsive to the. direot'current connected with the talking conductors upon the disconnecion of the inging current therefrom, and means operating upon the response of the relay to close the normally open talking condluctors.

v 9. A. telephone exchange systelncomprising a trunk circuit having normally open talking conductors extending from a first to a second switchboard, a link circuit at-the first switchboard connected with the trunk circuit, means in the link circuit for connecting a source of ringing current withthe bfllkillg condu tors, a source of direct current h fi t itchboa d, elink circuit Seri s, orthin, pa n may, boob ine responsive to the with the-talking conductors uponthe dl conwith the trunk circuit,a link inlay with ng the normally open talking conductors.

11;. A telephone exchange-system compristhe trunk circuit and non-responsive while connected therewith, but

ringing current is direct current connected nection oi thermgl-ng current therefrom,

and; a relay energized upon the response of the bridged relay to close th normally open talking strall l 10. A. telephone exo 'angesystein comprisinga trunk cirouitiextend nfrom a first toe second Swit h oard havingnormally open talking conductors enda signolin cond ctor, a ignaling de ice at the second switchboard, a link circuit at the ir t s itchboard, a relay energized over the signaling 0 docto upon the-connection of the link circui -withtho trunk circuit to operate the-signaling! device, a link circuit at the-second; s ltchlooa-rd, means 1n the runk c rcuit LQSPQDSlVfi to the conncct on of the Second link circuit therewith for connec ing the relay with. he tolking conductors, and meansresponsr e upon the. connection of the the talking conductors for o1osing a trunk circuit extending from a first to asecond switchboard and having normally open talking conductors and a signaling COIJClUQfi I,L S1gflllllng deviceat the seeone switchboard/a l'm-k circuit at the. first switchboard; a'relayoperating over the signahng conductor upon theconnection ofthe link circuit withthetrunlrcircuit to control thesignaling de. .ce; circuit at-the second switclfboard,'.-'re1ay in the trunk circuit responsivetothc connection of a-second link circuit therewith for disconnecting the first relay from the signaling conductor, a third relay cooperatin g with the second relay to connect thofirstrelay in bridge of the talking conductors,- means in the first link circuit for energizing the bridged relay, and

a fourth: relay responsive tOEa'thG'GIlQIgIZfL- tion of the bridged relay for closing the normally. open talking conductors.

In witness whereof, I: hereunto subscribe iny name this 8th day of May A. D. 1918. at the s cond switchboard, a relay connected 1 it in bridge ofthe talking conductors upon the iiiuc B. LUNDIUS. 

